Opened 16 years ago
Closed 16 years ago
#2435 closed defect (fixed)
GeoTIFF driver often redecodes pixel interleaved jpeg data
| Reported by: | warmerdam | Owned by: | warmerdam |
|---|---|---|---|
| Priority: | normal | Milestone: | 1.5.3 |
| Component: | GDAL_Raster | Version: | 1.5.2 |
| Severity: | normal | Keywords: | gtiff |
| Cc: |
Description
When MapServer uses GDAL to pull data from a JPEG compressed (or any pixel interleaved) geotiff file it does so in one pass per band. Currently this means that GDAL actually reads and decodes the data three (for RGB) times. For jpeg compressed data (for instance) this is pretty expensive.
It would be desirable if the GeoTIFF driver would push the unrequested bands of data into the block cache for faster subsequent access.
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I have implemented pushing into the block cache for the GTiffRasterBand in trunk (r14738) and 1.5 branch (r14739). The GTiffRGBABand would also benefit from this change, but I'm not readily setup to test it, and this class isn't widely used (I think).